Jessica SimpsonThe Super SecretWeight Watchers Diet Plan

11/26/2012 5:00 AM PST

Jessica Simpson -- The Super Secret Weight Watchers Diet Plan

EXCLUSIVE

Jessica Simpson kept herself to a strict Weight Watchers regimen in order to lose SIXTY POUNDS after her pregnancy -- a regimen filled with low-fat smoothies, protein, and veggies -- and TMZ has obtained her 4-month crash diet plan.

It all kicked off in July with a 15-day smoothie diet: 5 days of 3 smoothies a day (with 2 healthy snacks); 5 days of 2 smoothies a day (2 healthy snacks, 1 meal); and 5 days of 1 smoothie day (with 2 snacks and 2 meals).

For a while, it didn't look as if she'd lose any weight at all -- at least based on her terrible WW commercial -- so we gotta say ... we're impressed.